A low-cost mesocosm for the study of behaviour and reproductive potential in Afrotropical mosquito (Diptera: Culicidae) vectors of malaria.

A large-scale mesocosm was constructed and tested for its effectiveness for use in experiments on behaviour, reproduction and adult survivorship in the Afrotropical malaria vector Anopheles gambiae s.s. Giles (Diptera: Culicidae) in temperate climates. The large space (82.69 m(3) ) allowed for semi-natural experiments that increased demand on a mosquito's energetic reserves in an environment of widely distributed resources. A one-piece prefabricated enclosure, made with white netting and vinyl, prevented the ingress of predators and the egress of mosquitoes. Daylight and white materials prompted the mosquitoes to seclude themselves in restricted daytime resting sites and allowed the easy collection of dead bodies so that daily mortality could be assessed accurately using a method that accounts for the loss of a proportion of bodies. Here, daily, age-dependent mortality rates of males and females were estimated using Bayesian Markov chain Monte Carlo simulation. In overnight experiments, mosquitoes successfully located plants and took sugar meals. A 3-week survival trial with a single cohort demonstrated successful mating, blood feeding, oviposition and long life. The relatively low cost of the mesocosm and the performance of the mosquitoes in it make it a viable option for any behavioural or ecological study of tropical mosquitoes in which space and seasonal cold are constraining factors.

Abundance and bionomics of Ochlerotatus j. japonicus in two counties in southwestern Virginia.

Movement of Ochlerotatus japonicus japonicus into virus-endemic areas in the USA has raised concern about its vector potential and prompted monitoring of its spread. The abundance and seasonal distribution of Oc. japonicus in southwestern Virginia was measured in 2003 and 2004 using gravid traps. In 2003, collections were made over 192 trap-nights from June to August yielding 5,879 mosquitoes of which only 24 were Oc. japonicus. In 2004, 12,151 mosquitoes were trapped from June to September over 160 trap-nights. Ochlerotatus japonicus was the second most abundant mosquito species and the dominant Ochlerotatus species collected in gravid traps. Ochlerotatus japonicus was collected in low numbers in June, but the abundance increased significantly in July and remained consistent throughout the rest of the season. Of the other major mosquito species collected in this study, only Aedes albopictus exhibited a similar seasonal pattern as Oc. japonicus. Other biological similarities of Oc. japonicus and Ae. albopictus are discussed.

Surgery in the United Kingdom.

Surgery in the United Kingdom has been practiced for nearly 2000 years. It has evolved as a result of the experiences of warfare and the introduction of the scientific basis of surgery. The influence of the 4 surgical royal colleges in setting standards for training and examinations has ensured that new surgeons are equipped for independent practice as consultants. Responsibility for the National Health Service rests with the government, which determines the number of trainee surgeons in the various surgical specialties. Conflicts between service provision and training are highlighted, as are the pressures on academic institutions to meet the demands of clinical surgery. The government's National Health Service plan for England promises a major expansion in undergraduate places and an increase of 7500 consultants in all specialties by 2004. Time will tell if these changes lead to an improvement in surgical services and a reduction in waiting times.

Control of fetal insulin secretion.

In this study, we investigated the way in which fetal insulin secretion is influenced by interrelated changes in blood glucose and sympathoadrenal activity. Experiments were conducted in late gestation sheep fetuses prepared with chronic peripheral and adrenal catheters. The fetus mounted a brisk insulin response to hyperglycemia but with only a minimal change in the glucose-to-insulin ratio, indicating a tight coupling between insulin secretion and plasma glucose. In well-oxygenated fetuses, alpha(2)-adrenergic blockade by idazoxan effected no change in fetal insulin concentration, indicating the absence of a resting sympathetic inhibitory tone for insulin secretion. With hypoxia, fetal norepinephrine (NE) and epinephrine secretion and plasma NE increased markedly; fetal insulin secretion decreased strikingly with the degree of change related to extant plasma glucose concentration. Idazoxan blocked this effect showing the hypoxic inhibition of insulin secretion to be mediated by a specific alpha(2)-adrenergic mechanism. alpha(2)-Blockade in the presence of sympathetic activation secondary to hypoxic stress also revealed the presence of a potent beta-adrenergic stimulatory effect for insulin secretion. However, based on an analysis of data at the completion of the study, this beta-stimulatory mechanism was seen to be absent in all six fetuses that had been subjected to a prior experimentally induced hypoxic stress but in only one of nine fetuses not subjected to this perturbation. We speculate that severe hypoxic stress in the fetus may, at least in the short term, have a residual effect in suppressing the beta-adrenergic stimulatory mechanism for insulin secretion.

Intimal hyperplasia within biliary Wallstents: failure of recanalisation by insertion of a second endoprosthesis.

We report two patients with benign biliary strictures in whom we attempted recanalisation of metallic biliary endoprostheses, occluded by intimal hyperplasia, by the insertion of further endoprostheses within the occluded stents. Initial technical success was achieved in deploying the stents and restoring patency with elimination of mural filling defects. However, we found the intimal hyperplasia to be restrained for less than 48 h. From our initial results it appears that biliary metallic stent occlusion by intimal hyperplasia is not effectively treated by insertion of a second endoprosthesis.

The adrenal secretion of catecholamines during systemic metabolic acidosis in fetal sheep.

This study was undertaken to determine whether or not metabolic acidemia per se stimulates catecholamine (CA) secretion from the adrenal medulla in fetal sheep. The potential confounding effect of low O2 content, occasioned by the right shift in the oxyhemoglobin dissociation curve with acidemia, was taken into account in experimental design. Hemodynamic values, blood gases, O2 content, lactate and glucose concentrations and adrenal CA secretion rates and plasma CA levels were studied in fetal sheep at baseline and during control (saline infusion) and acidemic (15 and 30% lactic acid infusion) periods. Experiments were conducted after recovery from preparative operations performed under general anesthesia. Arterial pH did not change with saline infusion. During 15 and 30% lactic acid infusions, pH fell to 7.23 and 7.09, respectively, as lactate concentrations increased 4.7 and 10 times. Arterial PCO2 increased from 50 to 58 torr during 30% lactic acid infusion. Fetal CA secretion and plasma concentrations did not change during saline, or 15 or 30% lactic acid infusions. Moreover, hemodynamic parameters did not indicate increased CA secretion. In conclusion, we found no evidence for stimulation of adrenal CA secretion by metabolic acidosis.

Endoscopic tracheal obstruction with an expanding device in a fetal lamb model: preliminary considerations.

Tracheal obstruction to promote lung growth may be a less aggressive alternative to open fetal surgery in the antenatal treatment of congenital diaphragmatic hernia. Herein, we explore the feasibility of placing an occluding device through fetal tracheoscopy. A self-expanding umbrella allowed adequate sealing of the tracheal lumen even as the tracheal diameter more than doubled between 110 and 138 days of gestation (term = 145 days) in a sheep model. Distal intratracheal pressures after umbrella placement, and lung weight at delivery, were comparable to those after formal tracheal ligation.

Amyloid tumour of the rectum.

Systemic amyloidosis results in diffuse deposition of amyloid proteins in various organs. Localized deposits in the form of nodules also occur but are rare in the gastrointestinal tract. A localized amyloid deposit in the rectum that was clinically indistinguishable from carcinoma of the rectum or prostate is described.

Hypoxia-induced sympathetic inhibition of the fetal plasma insulin response to hyperglycemia.

Large-for-delivery date babies, considered characteristic of diabetic pregnancy, are believed to result from fetal hyperinsulinemia. Paradoxically, infant birth weights tend to be low-for-delivery date in mothers with more severe diabetes. We tested the hypothesis that hypoxemia in such fetuses leads to sympathoadrenal stimulation and inhibition of insulin secretion; and, thus, produces a net reduction in the growth-promoting effects. Fetal sheep were prepared with chronic peripheral and adrenal cannulas. Fetal blood gases, lactate, norepinephrine, and epinephrine secretion rates; and plasma norepinephrine, glucose, and immunoreactive insulin concentrations were determined at 30-min intervals during a 2-h baseline period and a 4-h period of hyperglycemia divided into 2-h segments of hypoxemia (with and without alpha-blockade) and hyperoxia. Hypoxemia-hyperoxia sequences were varied randomly. Well-oxygenated fetuses responded to a threefold increase in glucose with a sixfold increase in plasma immunoreactive insulin. With hypoxemia, norepinephrine and epinephrine secretion were elevated and the insulin response was blocked. With hypoxemia and phentolamine blockade, the insulin response was enhanced with a 10-fold increase above baseline. In severe maternal diabetes with vascular disease or with poor control and very high glucose levels, the fetus is likely to be relatively hypoxemic. Our experiments suggest that in this situation, the fetal insulin response to hyperglycemia will be attenuated; this effect is mediated, at least partly, through sympathoadrenal stimulation.

Randomized trial comparing diathermy hemorrhoidectomy with the scissor dissection Milligan-Morgan operation.

Twenty consecutive patients (12 male and 8 female) with second-degree, third-degree, or thrombosed hemorrhoids were randomly allocated to undergo either diathermy hemorrhoidectomy (n = 10) or a scissor dissection Milligan-Morgan hemorrhoidectomy (n = 10). No significant difference was found in the postoperative pain score between the groups. On a scale of 0 to 10, the mean daily pain score in the diathermy group was 4.0, and it was 4.1 in the scissor dissection group. Nor was there any significant difference in the length of inpatient stay (diathermy group, 3.5 days; scissor dissection group, 4.0 days) or in the time between the operation and the first bowel action (diathermy group, 2.0 days; scissor dissection group, 3.0 days). Diathermy hemorrhoidectomy has no significant advantage over the scissor dissection classical Milligan-Morgan hemorrhoidectomy.

Adrenal corticosteroid secretion in fetal sheep: pulsatile pattern at rest.

This study was undertaken to define the resting pattern of fetal pituitary-adrenocortical function. Experiments were performed at 127-145 days gestation in fetal sheep with chronic peripheral and adrenal cannulas inserted under halothane anesthesia. With the fetus in a baseline state, over 6 h, at 30-min intervals, maternal and fetal peripheral samples were collected for blood gases and cortisol (F), corticosterone (B), and adrenocorticotropic hormone (ACTH) concentrations, and three successive, 2-min adrenal samples were collected for determination of F and B secretion rates. We observed high-frequency, episodic bursts of F secretion. A lower frequency oscillation of F secretion, with a period of approximately 90 min, was defined by cosinor analysis. The mean amplitude of the oscillation increased from 45 to 507 ng/min with advancing gestation. The pattern of B secretion was similar to that for F but was quantitatively lower. An oscillatory period of approximately 90 min for plasma F was present in a majority of experiments. Pulsatile rhythms for ACTH were defined in 10 of 14 experiments, with periods ranging from 1.64 h in the least mature group to 2.37 h in the oldest fetus. Mean data revealed exponential increases in both F secretion and plasma ACTH from 129 to 145 days gestation.

The effect of hyperglycemia on acid-base and sympathoadrenal responses in the hypoxemic fetal monkey.

We investigated the influence of hyperglycemia on the fetal acid-base and sympathoadrenal responses to hypoxemia (maternal FIO2 9%) in rhesus monkey fetuses. In chronic preparations, we determined PO2, O2 content, PCO2, pH, lactate, glucose, insulin, catecholamines, heart rate, and arterial pressure. Combined hyperglycemia and hypoxemia resulted in a decrease in fetal pH and an increase in lactate; however, the magnitude of these changes was only modestly, and not significantly, greater than those observed during euglycemic hypoxemia. These effects were much less striking than expected, based on earlier work in sheep (Shelley, Bassett & Milner, 1975; Robillard, Sessions, Kennedy & Smith, 1978). Although catecholamines increased significantly in response to hypoxemia both in hyperglycemic and euglycemic fetuses, the increase was less in the hyperglycemic group, possibly resulting from a modulating effect of the high glucose concentration on catecholamine release from the adrenal medulla. Finally, a significant fetal insulin response to hyperglycemia was seen which, suggestively, was partially inhibited in the presence of hypoxemia and its associated increase in sympathoadrenal activity.

Effects of anesthetic agents and abdominal surgery on liver blood flow.

The cause of postoperative liver dysfunction is often unclear, but a decrease in liver blood flow during anesthesia and/or major surgery may be important. Plasma half-life and clearance of indocyanine green were therefore measured in 42 patients before, during and after anesthesia and abdominal surgery. In 13 patients, liver blood flow was also estimated from indocyanine green extraction using hepatic vein catheterization. The major finding was an early decrease in estimated liver blood flow after induction of anesthesia, but not later during or after surgery. Mean indocyanine green half-life increased by 26% (p less than 0.005), mean indocyanine green plasma clearance decreased by 19% (p less than 0.01) and mean estimated hepatic blood flow decreased by 36% (p less than 0.005) during the first 30 min of anesthesia. These changes were greater in males and in patients older than 55 yr, but changes were similar with each of three anesthetic groups. Half-life, but not indocyanine green clearance, was also significantly prolonged by mid-operation in the older (greater than 55 yr) patients and in those undergoing lower abdominal surgery. We suggest that this period of reduced liver blood flow during anesthesia is caused by the effects of neuromuscular blocking agents and may contribute to postoperative liver damage.

Sympathoadrenal responses during hypoglycemia, hyperinsulinemia, and hypoxemia in the ovine fetus.

Interrelations of sympathoadrenal function and changes in glucose and insulin homeostasis were studied in chronically cannulated late gestation fetal sheep. Catecholamine secretory rates (based on direct adrenal sampling) and plasma concentrations were determined in the fetus during 2 h of insulin-induced hypoglycemia, during a period of hypoxemia, and during hyperinsulinemia per se (i.e., without hypoglycemia). Fetal insulin infusion (5-10 mU.kg-1.min-1) resulted in hypoglycemia and a significant rise in secretion of epinephrine but not of norepinephrine. By contrast, fetal hypoxemia caused a prompt and significant increase in adrenal secretion of both norepinephrine and epinephrine. Changes in peripheral plasma catecholamine levels were usually, but not always, qualitatively similar to those in adrenal secretion; the latter was a far more sensitive indicator of adrenal function. Hyperinsulinemia per se caused no change in adrenal secretory rates or plasma concentrations of catecholamines. Nevertheless, insulin infusion caused a fetal tachycardia even in the absence of hypoglycemia and hypoxemia, suggesting either a direct effect on the heart or stimulation of sympathetic nerves.

Primary extranodal non-Hodgkin's lymphoma of the extrahepatic biliary tract.

A case of extranodal non-Hodgkin's diffuse, mixed small and large cell lymphoma of the extrahepatic biliary tract with jaundice as the initial manifestation is reported in this paper. Obstructive jaundice is very rarely an early symptom in lymphoma. The pathogenesis of jaundice in this case was infiltration of the extrahepatic bile duct by lymphoma cells and fibrosis.

Adrenal secretion of glucocorticoids during hypoxemia in fetal sheep.

This work was undertaken to investigate the fetal adrenal corticoid secretory response to hypoxic stress in late gestation. Experiments were performed in two groups of fetal sheep of different gestational ages, group I, 129-132 (mean, 130) days and group II, 135-139 (mean, 136) days. Fetuses were prepared with chronic adrenal cannulas as well as peripheral arterial and venous catheters. With the fetus at rest and after 7, 9, 11 and, in some instances, 30 and 60 min of hypoxia (maternal FIO2 10%), precisely timed (2 min) samples of adrenal effluent were collected for determination of cortisol (F) and corticosterone (B) secretion rates. Peripheral samples were obtained intermittently for blood gas and lactate determinations. Resting corticoid secretory rates were highly variable, suggesting an episodic secretory pattern. Corticoid secretory responses to hypoxemia were significantly elevated at 7-11 min, peaked at 30 min, and remained stable at 60 min. Specifically, in group I, F secretion increased from a baseline value of 37 +/- 19 ng/min to a peak hypoxemic response of 376 +/- 80 ng/min; B secretion increased from 6 +/- 4 to 170 +/- 32 ng/min. In group II, F secretion increased from 99 +/- 20 to 653 +/- 107 ng/min; B secretion increased from 12 +/- 5 to 200 +/- 28 ng/min. When related to adrenal gland weight, there was no difference between F secretory responses in groups I and II, whereas relative B secretory responses were lower in group II than in group I at 9 and 11 min of hypoxemia. We conclude that the 129-139 day sheep fetal adrenal cortex is highly sensitive to hypoxic stress with the effect presumably mediated by elevated levels of endogenous ACTH. The B stress response decreases as gestational age advances from the 129-132 day range to 135-139 days.

Invasion and metastasis following orthotopic transplantation of human pancreatic cancer in the nude mouse.

A good experimental model for metastasis of human pancreatic cancer would be a valuable tool for the study of this process, which contributes significantly to morbidity and mortality. Models of experimental metastasis using injection of tumor cells into the portal or systemic circulation bypass some important steps of the metastatic process. We describe invasion and metastasis following orthotopic transplantation of human pancreatic carcinoma into nude mice. Tumor pieces were used as xenografts in this study, and metastases were observed in the regional lymph nodes, liver, lungs, and distant lymph nodes of the animals. Peritoneal implants and ascites were not observed in this study. Orthotopic transplantation of human pancreatic cancer in the nude mouse appears to be a promising model of spontaneous metastasis relevant to clinical reality.

Effects of insulin infusion on plasma catecholamine concentration in fetal sheep.

To evaluate the response of the sympathoadrenal system in fetal sheep receiving exogenous insulin infusion, we measured plasma catecholamine levels in 14 chronically catheterized fetal sheep before and during an infusion of insulin for 2 days. Catecholamine values were measured in fetal arterial plasma by an electrochemical detection method. Fetal plasma norepinephrine and epinephrine concentrations increased significantly during insulin infusion. Significant inverse correlations were observed between the log norepinephrine concentration and fetal arterial oxygen content and glucose values. A significant direct correlation between the log norepinephrine concentration and fetal arterial carbon dioxide concentration was also observed. The log epinephrine concentration correlated inversely with plasma glucose concentration. Increases in fetal heart rate during both the noninfused and insulin-infused states correlated significantly with increases in norepinephrine concentration. We conclude that the sympathoadrenal system is activated during fetal insulin infusion, potentially supporting some of the fetal cardiovascular responses to insulin infusion.